This is a real curiosity: the first revival in 50 years of a totally forgotten JB Priestley play. It exhibits Priestley's formidable strengths, and occasional frailties, in that a fierce moral sense, reminiscent of An Inspector Calls, is combined with a reluctance to let the characters escape the author's control.

Written for Toronto's Crest Theatre, the play is set in one of that city's more rigidly religious households in 1906. The McBanes are a pious, Bible-thumping lot, dominated by the bullying David and his bachelor brother, Malcolm. Into their midst comes a strange trio of siblings, the fruits of a marriage between a third, wild McBane brother and a Native American woman. As the three disrupt the puritanical household with their boozing and sexual seduction, we are kept in the dark as to their ultimate purpose. Finally, Priestley makes it clear that they are hell-bent on revenge for the way their late dad was cheated of his rightful inheritance.

Priestley, as we know from his earlier work, is an expert at undermining bourgeois hypocrisy. We watch with mounting pleasure as he skilfully unpicks the dark and dirty secrets of the Presbyterian McBanes. Priestley created the play at a time when he had become disenchanted with transatlantic materialism and his wife was busy exploring the life of Native American tribes, so he writes well about the collision of two cultures. Yet there is something schematic about the way he shows the intruders releasing the Dionysiac instincts of their strait-laced female cousin and her theological boyfriend. In attacking a life-denying religious orthodoxy, Priestley shows himself to be the architect of an inflexible dramatic structure.

Laurie Sansom's first-rate production invests the proceedings with an aura of creepiness. Adam Cork's music and sound-score, with its mixture of hymns and hums, scrapes insistently on the nerves. Rebecca Grant leads the siblings with great verve, at one point launching into a frenzied bacchanalian dance. And there is fine work from John Arthur as the poker-backed patriarch, Robert Demeger as his lecherous brother and Robin Bowerman who, as the family doctor, displays the most flawless Canadian accent I have heard from an English actor. I wouldn't class this among Priestley's greatest plays, but for its attack on fundamentalist piety and purblind revenge, it certainly justifies revival.

· Until November 17. Box office: 01604 624811.

· This article was amended on Tuesday November 13 2007. We named two of the characters as John and Robert McBane. They are David and Malcolm, played in this production by John Arthur and Robert Demeger. This has been corrected.